In recent years, technique of composing thin film transistors (TFT) by using a semiconductor thin film (with a thickness of approximately several to several hundreds nm) formed over a substrate having an insulating surface has attracted attention. A thin film transistor is widely applied to an electronic device such as an IC or an electro-optic device, and is especially developed as a switching element for an image display device.
As an image display device, a liquid crystal display device is generally well known. An active matrix liquid crystal display device is used more often as an image display device than a passive matrix liquid crystal display device since the active matrix liquid crystal display device can achieve a higher definition image than that of the passive matrix liquid crystal display device. In an active matrix liquid crystal display device, a display pattern is formed on a screen by driving pixel electrodes arranged in a matrix configuration. Specifically, upon being applied voltage between a selected pixel electrode and an opposing electrode corresponding to the pixel electrode, optical modulation of a liquid crystal layer interposed between the pixel electrode and the opposing electrode is occurred, and the optical modulation is recognized by a viewer as a display pattern.
Conventionally, production technique of performing efficiently mass production by clipping a plurality of liquid crystal display panels from one mother glass substrate has been adopted. The mother glass substrate has grown in size from a first generation at the start of 1990s, 300×400 mm to a fourth generation in 2000 s, 680×880 mm or 730×920 mm. Simultaneously, production technique has been progressed so that multiple display panels can be obtained from one substrate.
In recent years, study of a light-emitting device having an EL element as a self luminous light-emitting element has been activated. The light-emitting device is also referred to as an organic EL display or an organic light-emitting diode. These light-emitting devices have attracted attention as a new generation cellular phone, a personal digital assistance (PDA), or a next generation display for their characteristics of high speed response speed that is suitable for movie display; low voltage; low power consuming driving; and the like.
An EL element comprises an anode, a cathode, and a layer containing an organic compound as a light-emitting layer (hereinafter, EL layer) that is interposed between the anode and the cathode. Upon applying voltage to the anode and the cathode, light is emitted from the EL layer (Electro Luminescence). Fluorescence that occurs from the singlet excited state back down to the ground state and phosphorescence that occurs from the triplet excited state back down to the ground state are obtainable from the EL element.
The application range of an active matrix display device has been expanded. Requirements of high definition, a high opening ratio, and high reliability have been increased as increasing the size of a screen.
Unexamined patent publication No. 2000-298446 discloses that a large display can be realized by forming one display screen composed of a plurality of tiled panels. However, the large display requires high costs and a unique driving method since a plurality of panel is used.
Simultaneously with increasing the screen size, requirements of improvement of productivity and reduction in costs have been increased.
Unexamined patent publication No. 2000-188251 discloses technique for forming a film over a semiconductor wafer by using a device that can deliver continuously resist solution in the form of a line having a thin diameter to improve the yield of the solution used for film formation.